The present invention relates generally to barcode scanners, and, more specifically, to rotary spinners therein.
Presentation and pass-by type barcode scanners include rotating spinners for reflecting a laser beam to project a scan line pattern across a barcode for scanning and decoding thereof. The spinner includes a row of mirror facets arranged in a polygon for segmenting the laser beam and reflecting the beam segments from cooperating pattern mirrors specifically oriented in the barcode scanner for producing the desired pattern of scan lines.
Since the pattern is repeated once per revolution of the spinner, the spinner facets and the cooperating pattern mirrors must be precisely positioned to produce the desired pattern of limited number of scan lines for the outbound scan beam, as well as collecting sufficient light in the inbound reverse path through the pattern mirrors and spinner for decoding thereof. Whereas the outbound scan beam is distinct and bright, the inbound collection light is diffuse from reflecting off the barcode at various angles.
Accordingly, optical performance of the barcode scanner is directly affected by the configuration of the rotary spinner and its mirror facets. The spinner rotates at a relatively high speed of about 4,000-8,000 rpm, for example, for producing an effective scanning pattern, with the spinner facets being sufficiently large for collecting sufficient inbound return light for decoding the barcode.
However, the relatively large spinner facets and the high rotational speed thereof create substantial windage drag in the typical air environment. Windage requires a suitably powerful motor for rotating the spinner to overcome the air drag forces. And, windage produces substantial aerodynamically generated noise from the rotating spinner during operation. Audible noise from the operating spinner is undesirable and should be minimized in commercially competitive barcode scanners.
However, the form and size of the spinner facets directly affect windage and noise generated during operation, and are typically determined by the desired optical performance of the scanner.
Typical spinners may include three, four, five, or more facets arranged in a polygon around a common rotary axis in a generally axisymmetrical configuration. In a recent development, a four-faceted rectangular spinner enjoys certain advantages in the resulting scan line pattern produced therefrom. The rectangular spinner experiences even greater windage and greater noise during operation which undesirably detract from the improved optical performance thereof.
Accordingly, it is desired to provide a streamlined barcode spinner for reducing windage drag without reducing optical performance.
A spinner for a barcode scanner includes mirror facets arranged in a polygon about a rotary axis. A fairing extends radially outwardly from adjacent the facets, and is circumferentially truncated therearound for aerodynamically streamlining the spinner.